Influence of systemic herbicides on tuber suppression of yellow nutsedge ( <i>Cyperus esculentus</i> )

Abstract Yellow nutsedge is a perennial weed that widely infests turf. Herbicides such as glyphosate and acetolactate synthase (ALS)‐inhibiting herbicides like halosulfuron are commonly used to treat yellow nutsedge, but over reliance upon these herbicides has resulted in resistant populations. The objective of this research was to assess the strategy of mixing ALS‐inhibiting herbicides with glyphosate for yellow nutsedge control, with a focus on tuber production and viability. Yellow nutsedge single shoots were established in large planter pots containing field soil. Note that 7 weeks after establishment, treatments were applied to yellow nutsedge at the flowering stage. Treatments included single applications of glyphosate, imazaquin, or halosulfuron at the suggested label rate or the label rate of glyphosate in mixture with either 0.75× or 1× label rates of imazaquin or halosulfuron, in addition to an untreated control. By 4 weeks after treatment (WAT), &gt;50% shoot injury was observed with all treatments containing halosulfuron. At 6 WAT, tuber production was reduced by 86% or greater for halosulfuron‐containing treatments compared to the untreated control. This effect was comparable to tank mixing the labeled rate of imazaquin with glyphosate. Tuber emergence was 68% for the untreated control, and treatments containing halosulfuron or glyphosate in tank mixture with the labeled rate of imazaquin reduced tuber emergence to 4.2% or less. This research suggests that combinations of halosulfuron or imazaquin with glyphosate constitute an effective control strategy that reduces the potential to select for resistant yellow nutsedge.